The present invention relates to the preparation of 2-hydroxytetrahydrofuran through the utilization of a highly selective catalyst system and more specifically to the preparation of tetrahydrofuran from 2-hydroxytetrahydrofuran.
Heretofore, various catalysts have been utilized in hydroformylation reactions. Among these catalysts are various rhodium compounds or complexes such as acetyl acetonate rhodium dicarbonyl. Another specific catalyst is hydridocarbonyltris[triphenyl phosphine]-rhodium which has been used in the hydroformylation of alkenes at atmospheric pressure, see Journal of the chemical Society [A] 1970, Pages 2753-2764. Additionally, similar rhodium compounds or complexes have been utilized to prepare 1,4-butanediol as set forth in U.S. Defensive Publication No. T904,021 or to hydroformylate alpha-olefins as in U.S. Pat. No. 3,527,809 and the Journal of Organic Chemistry, Vol. 34, No. 2, February, 1969, pp. 327-330.
Applicant's process relates to the preparation and production of 2-hydroxytetrahydrofuran utilizing a rhodium complex which has been found to be very selective to the formation of a specific intermediate which readily yields said 2-hydroxytetrahydrofuran compound.
Additionally, tetrahydrofuran is readily prepared from 2-hydroxytetrahydrofuran by dehydration followed by hydrogenation. Although the literature reports that substituted 2hydroxytetrahydrofuran can be dehydrated by simple distillation, Botteghi et al, Journal of Organic Chemistry, Volume 37, No. 11, 1972, pp. 1835-1837, it has been found that non-substituted 2-hydroxytetrahydrofuran cannot be dehydrated except with the use of specific dehydration catalysts. Moreover, the prior art in dehydrating substituted 2-hydroxytetrahydrofuran often utilizes acid catalysts such as anhydrous oxalic acid, copper sulfate, ammoniun nitrate, and the like, Botteghi, Gazzetta Chimica Italiana, 105 (1975) pp. 233-245. However, the effect of such acid catalysts upon a non-substituted 2-hydroxytetrahydrofuran solution would result in chain opening of the furan ring to yield an aldehyde compound and, thus, prevent any possible formation of tetrahydrofuran. On the contrary, the catalysts of the present invention will readily permit dehydration of non-substituted 2-hydroxytetrahydrofuran.